Engine shutdown valves are well known accessories on both stationary and mobile engine applications around the world, and have been in use for over forty years. The basic reason for installing a shutdown valve is to have a safety device that allows control over the operation of an engine. The most common justification for this need is to terminate the operation of a diesel engine when an uncontrolled over-speed results from the inhalation of combustible vapors through the engine air cleaner. Without such a shutdown device the engine may continue over-speeding until catastrophic failure occurs. By shutting off the air intake manifold, the shutdown valve starves the engine of oxygen (and the secondary fuel source) and terminates combustion in the cylinders, therefore preventing damage caused by uncontrolled over-speed. Other applications result from the basic need to have a positive means of shutting down an engine.
Engine shutdown valves with reciprocating gates are known from U.S. Pat. No. 4,285,494 issued Aug. 25, 1981, U.S. Pat. No. 4,501,238, issued Feb. 26, 1985, and U.S. Pat. No. 5,205,252, issued Apr. 27, 1993. This invention is an improvement in the art of shutdown valves with reciprocating gates, and provides a compact and reliable device that is easy to make and operate.